Chinese hamster ovary cells continuously secrete a cysteine endopeptidase.
The protease activity in serum-free conditioned medium of chinese hamster ovary (CHO) cells was measured using peptidyl (or aminoacyl)-4-methylcoumaryl-7-amides (MCAs) as the substrates. Aminopeptidase increased in level as amounts of nonviable cells increased during cultivation in serum-free medium, indicating that the activity seems to be originated from intracellular proteases. The activity toward Boc-Leu-Arg-Arg-MCA, which was strongly inhibited by p-chloromercuribenzonate and N-ethylmaleimide, was the strongest among those toward peptidyl-MCAs in the conditioned medium within 48 h-cultivation in serum-free medium. In contrast to the case of aminopeptidase activity, the endopeptidase activity decreased in level after 48 h-cultivation although amounts of nonviable cells increases. Thus, CHO cells continuously secrete the cysteine proteases.
Satoh
M
M
Tokyo Research Laboratories, Kyowa Hakko Co., Ltd., Japan.
Hosoi
S
S
Sato
S
S
D000626:Aminopeptidases / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D005260:Female; D006868:Hydrolysis; D010053:Ovary / Q000166:cytology* / Q000378:metabolism; D013762:Tetrahydrofolate Dehydrogenase / Q000378:metabolism
D013762:Tetrahydrofolate Dehydrogenase; D000626:Aminopeptidases; D003546:Cysteine Endopeptidases